This invention relates to an apparatus for checking a trouble produced in a circuit or system and, more particularly to a trouble checking apparatus which provides a graphic presentation of a defective region or regions included in the system.
Trouble checking apparatus have been used in checking a defective region or regions of an electronic engine control circuit (C/U) used in an automotive vehicle for controlling the engine based upon vehicle opera ting conditions sensed by various sensors including an engine coolant temperature sensor, an idle switch, a transmission neutral position switch, etc. The conventional trouble checking apparatus employs a digital computer communicated with the engine control circuit. The digital computer includes a central processing unit and a memory. The central processing unit processes the data input ted from the engine control circuit, the data inputted through a keyboard and the data stored in the memory to make trouble checks for the engine control circuit. The check results are displayed on a display unit. With the conventional trouble checking apparatus, however, the check results are displayed in the form of short sentences comprised of characters. Therefore, it is difficult for the operator to seize the entire picture of the defective condition of the checked circuit or system.